/*
* Copyright 2009 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

using System.Collections.Generic;

namespace ZXing.Multi
{
   /// <summary>
   ///   <p>Attempts to locate multiple barcodes in an image by repeatedly decoding portion of the image.
   /// After one barcode is found, the areas left, above, right and below the barcode's
   /// {@link com.google.zxing.ResultPoint}s are scanned, recursively.</p>
   ///   <p>A caller may want to also employ {@link ByQuadrantReader} when attempting to find multiple
   /// 2D barcodes, like QR Codes, in an image, where the presence of multiple barcodes might prevent
   /// detecting any one of them.</p>
   ///   <p>That is, instead of passing a {@link Reader} a caller might pass
   ///   <code>new ByQuadrantReader(reader)</code>.</p>
   ///   <author>Sean Owen</author>
   /// </summary>
   public sealed class GenericMultipleBarcodeReader : MultipleBarcodeReader, Reader
   {
      private const int MIN_DIMENSION_TO_RECUR = 30;
      private const int MAX_DEPTH = 4;

      private readonly Reader _delegate;

      /// <summary>
      /// Initializes a new instance of the <see cref="GenericMultipleBarcodeReader"/> class.
      /// </summary>
      /// <param name="delegate">The @delegate.</param>
      public GenericMultipleBarcodeReader(Reader @delegate)
      {
         this._delegate = @delegate;
      }

      /// <summary>
      /// Decodes the multiple.
      /// </summary>
      /// <param name="image">The image.</param>
      /// <returns></returns>
      public Result[] decodeMultiple(BinaryBitmap image)
      {
         return decodeMultiple(image, null);
      }

      /// <summary>
      /// Decodes the multiple.
      /// </summary>
      /// <param name="image">The image.</param>
      /// <param name="hints">The hints.</param>
      /// <returns></returns>
      public Result[] decodeMultiple(BinaryBitmap image, IDictionary<DecodeHintType, object> hints)
      {
         var results = new List<Result>();
         doDecodeMultiple(image, hints, results, 0, 0, 0);
         if ((results.Count == 0))
         {
            return null;
         }
         int numResults = results.Count;
         Result[] resultArray = new Result[numResults];
         for (int i = 0; i < numResults; i++)
         {
            resultArray[i] = (Result)results[i];
         }
         return resultArray;
      }

      private void doDecodeMultiple(BinaryBitmap image, IDictionary<DecodeHintType, object> hints, IList<Result> results, int xOffset, int yOffset, int currentDepth)
      {
         if (currentDepth > MAX_DEPTH)
         {
            return;
         }

         Result result = _delegate.decode(image, hints);
         if (result == null)
            return;

         bool alreadyFound = false;
         for (int i = 0; i < results.Count; i++)
         {
            Result existingResult = (Result)results[i];
            if (existingResult.Text.Equals(result.Text))
            {
               alreadyFound = true;
               break;
            }
         }
         if (!alreadyFound)
         {
            results.Add(translateResultPoints(result, xOffset, yOffset));
         }

         ResultPoint[] resultPoints = result.ResultPoints;
         if (resultPoints == null || resultPoints.Length == 0)
         {
            return;
         }
         int width = image.Width;
         int height = image.Height;
         float minX = width;
         float minY = height;
         float maxX = 0.0f;
         float maxY = 0.0f;
         for (int i = 0; i < resultPoints.Length; i++)
         {
            ResultPoint point = resultPoints[i];
            if (point == null)
            {
               continue;
            }
            float x = point.X;
            float y = point.Y;
            if (x < minX)
            {
               minX = x;
            }
            if (y < minY)
            {
               minY = y;
            }
            if (x > maxX)
            {
               maxX = x;
            }
            if (y > maxY)
            {
               maxY = y;
            }
         }

         // Decode left of barcode
         if (minX > MIN_DIMENSION_TO_RECUR)
         {
            doDecodeMultiple(image.crop(0, 0, (int)minX, height), hints, results, xOffset, yOffset, currentDepth + 1);
         }
         // Decode above barcode
         if (minY > MIN_DIMENSION_TO_RECUR)
         {
            doDecodeMultiple(image.crop(0, 0, width, (int)minY), hints, results, xOffset, yOffset, currentDepth + 1);
         }
         // Decode right of barcode
         if (maxX < width - MIN_DIMENSION_TO_RECUR)
         {
            doDecodeMultiple(image.crop((int)maxX, 0, width - (int)maxX, height), hints, results, xOffset + (int)maxX, yOffset, currentDepth + 1);
         }
         // Decode below barcode
         if (maxY < height - MIN_DIMENSION_TO_RECUR)
         {
            doDecodeMultiple(image.crop(0, (int)maxY, width, height - (int)maxY), hints, results, xOffset, yOffset + (int)maxY, currentDepth + 1);
         }
      }

      private static Result translateResultPoints(Result result, int xOffset, int yOffset)
      {
         var oldResultPoints = result.ResultPoints;
         var newResultPoints = new ResultPoint[oldResultPoints.Length];
         for (int i = 0; i < oldResultPoints.Length; i++)
         {
            var oldPoint = oldResultPoints[i];
            if (oldPoint != null)
            {
               newResultPoints[i] = new ResultPoint(oldPoint.X + xOffset, oldPoint.Y + yOffset);
            }
         }
         var newResult = new Result(result.Text, result.RawBytes, newResultPoints, result.BarcodeFormat);
         newResult.putAllMetadata(result.ResultMetadata);
         return newResult;
      }

      /// <summary>
      /// Locates and decodes a barcode in some format within an image.
      /// </summary>
      /// <param name="image">image of barcode to decode</param>
      /// <returns>
      /// String which the barcode encodes
      /// </returns>
      public Result decode(BinaryBitmap image)
      {
         return _delegate.decode(image);
      }

      /// <summary>
      /// Locates and decodes a barcode in some format within an image. This method also accepts
      /// hints, each possibly associated to some data, which may help the implementation decode.
      /// </summary>
      /// <param name="image">image of barcode to decode</param>
      /// <param name="hints">passed as a <see cref="IDictionary{TKey, TValue}"/> from <see cref="DecodeHintType"/>
      /// to arbitrary data. The
      /// meaning of the data depends upon the hint type. The implementation may or may not do
      /// anything with these hints.</param>
      /// <returns>
      /// String which the barcode encodes
      /// </returns>
      public Result decode(BinaryBitmap image, IDictionary<DecodeHintType, object> hints)
      {
         return _delegate.decode(image, hints);
      }

      /// <summary>
      /// Resets any internal state the implementation has after a decode, to prepare it
      /// for reuse.
      /// </summary>
      public void reset()
      {
         _delegate.reset();
      }
   }
}
